1. Field of the Invention
The present invention relates to a bonding agent sticking inspection apparatus for inspecting a sticking state of a bonding agent such as an anisotropic conductive film stuck on a glass substrate of, for example, a liquid crystal panel. Further, the present invention relates to a mounting apparatus provided with a bonding agent sticking inspection apparatus for inspecting a sticking state of a bonding agent such as an anisotropic conductive film stuck on a glass substrate of, for example, a liquid crystal panel. Furthermore, the present invention relates to a method of manufacturing an electrical component including a bonding agent sticking inspection step for inspecting a sticking state of a bonding agent such as an anisotropic conductive film stuck on a glass substrate of, for example, a liquid crystal panel.
2. Description of the Related Art
On an electronic component such as a liquid crystal panel, a semiconductor chip, and a flexible substrate are mounted by a mounting system provided with a plurality of units for performing various types of processing.
The mounting system is provided with a unit for supplying a liquid crystal panel, a unit for mounting a semiconductor chip on the liquid crystal panel, a unit for mounting a flexible substrate on the liquid crystal panel on which the semiconductor chip is mounted, a unit for collecting the liquid crystal panel subjected to the various mounting operations, and the like. The liquid crystal panel is successively sent to the unit for supplying a semiconductor chip, the unit for supplying a flexible substrate, and the unit for collecting the liquid crystal panel, and is subjected to the various operations.
Each of the unit for mounting a semiconductor chip on the liquid crystal panel, and the unit for mounting a flexible substrate on the liquid crystal panel is provided with a mounting apparatus for mounting each component on the liquid crystal panel. The mounting apparatus is provided with a bonding agent sticking apparatus for sticking a bonding agent such as an anisotropic conductive film on an electrode of the liquid crystal panel, a pressure bonding apparatus for pressure-bonding the semiconductor chip and the flexible substrate to the bonding agent, and the like. The bonding agent is interposed between the electrode and the semiconductor chip, and between the electrode and the flexible substrate in order that the electrode and the semiconductor chip, and the electrode and the flexible substrate may be electrically connected to each other.
The bonding agent is put on a base tape having no adhesion, and wound into a reel-like shape to be held. A necessary length of the bonding agent is cut from the reel, stuck on the liquid crystal panel, and thereafter the base tape is peeled off.
If any shortage of the bonding agent is caused, at the part in which a shortage of the bonding agent is caused, no bonding agent is interposed between the electrode of the liquid crystal panel and the semiconductor chip, or between the electrode and the flexible substrate. Particularly, when the base tape is removed after the bonding agent is stuck on the liquid crystal pane, the peripheral edge part of the bonding agent is liable to be chipped off.
When no bonding agent is interposed between the electrode and the semiconductor chip, or between the electrode and the flexible substrate, the electrical connection at these parts is liable to be canceled. It is not desirable that a nick of such a size that the electrical connection is hindered is formed in the bonding agent.
For this reason, a mounting apparatus for mounting a semiconductor chip or a flexible substrate is provided with an inspection apparatus for inspecting whether or the nick caused in the bonding agent has a size that causes a hindrance. An inspection for checking whether or not the size of the nick of the bonding agent is within a normal range is carried out by using the inspection apparatus before the semiconductor or the flexible substrate is mounted on the liquid crystal panel.
An inspection apparatus of such a type is provided with a camera. A picture of a range of a glass substrate in which the bonding agent must be positioned is taken by the camera. When a nick is present in the bonding agent, the luminance in the photographed image at the part in which the nick is present is different from that of the part in which the bonding agent is normally stuck.
The inspection apparatus divides the luminance components of the parts in the photographed image into those of abnormal parts (parts in which a nick or the like is present) and those of normal parts by using a threshold. Further, the inspection apparatus performs binarization processing in which, for example, normal parts are blackened, and parts in which a nick is present are whitened. The inspection apparatus judges whether or not a nick formed in the bonding agent is within a normal range by detecting the number of pixels of the abnormal part, and comparing the total number of pixels of the abnormal part with a threshold.
The bonding agent is cut when it is stuck, and the base tape is peeled off from the cut end part of the bonding agent, and hence a nick is liable to occur at the end part. Thus, when the bonding agent is inspected, inspecting only both end parts of the bonding agent has been performed.
However, it can be considered that a nick may occur at parts other than the both end parts, and hence inspecting the entire bonding agent is performed. A technique of such a type is disclosed in, for example, Jpn. Pat. Appln. KOKAI Publication No. 2001-21333.
On the other hand, a nick formed in a bonding agent stuck on the liquid crystal panel has, even when the nick has a size larger than the threshold, a shape that hinders the electrical connection or a shape that does not hinder the electrical connection. This point will be specifically described below.
A plurality of electrodes are formed on the liquid crystal panel, and are arranged side by side with each other in one direction. Accordingly, when the nick is extended in the direction in which the plural electrodes are arranged, and a part overlapping the nick is small in each electrode, the electrical connection is not hindered in some cases even if the size of the nick is larger than the threshold.
Conversely, when the size of the nick is larger than the threshold, and the nick has a shape overlapping, for example, an electrode, it becomes impossible for the electrode to be connected to the semiconductor chip or the flexible substrate. In this case, the electrical connection between the electrode and the semiconductor chip, and the electrical connection between the electrode and the flexible substrate are hindered.
In the inspection apparatus and the inspection method disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2001-21333, an abnormality in the stuck bonding agent is judged by the total number of pixels indicating the nick. Thus, as described above, it is considered that even when a shape of the nick is a shape that does not hinder the electrical connection, it may possibly be judged that there is an abnormality in the bonding agent.
It is therefore not desirable that the bonding agent be judged as abnormal if the nick does not hinder the electrical connection.